one thing is that the sova is about the only capital ship that can hurt an enemy planet (via embargo) and destroy structures (via bombers) while still sitting at the end of a grav well, ready to leave at a moment's notice. while the embargo rush is more of a strategy than an actual ship strengh, its fairly powerful. it comes with risks, but I'd say the potential benefits outweigh the risks, especially since you can get it out of the source grav well easy and don't have to bother with gauss canons. that means that even if the enemy retreats his capital to his hw, you can pull out nicely have siphoned off resources, maybe destroyed a structure and go back again. if the enemy uses his capship to attack your hw, you can also just start bombing him down. considering you take of his income, I'd say you are in the better position here.
In early Sova levels, taking Embargo means not taking squadron damage bonus and missile platform abilities, and the only way to effectively hurt a player is to embargo their homeworld because it generates a disproportionate income compared to all the rest. Aside from the obvious risk of sitting that deep in someone's space, by pumping points into Embargo you deny your Sova missile platforms and squadron damage, leaving yourself with a very weak combat ship. And while the Sova sits there and siphons off some credit income, the enemy is effectively without a flagship and your own can go to town on 'em

second, the flaks you mention are lvl 2. its early, but it can be late enough in smaller games. I would even say the sova shines especially early on in smaller games. because right from the start the bombers cannot really be countered. its of course scouting work to determine what strategy the enemy employs, but I'd say it will take less time getting your flagship to the enemy hw that it does your opponent going straight for flaks and building them, which again assumes that he knows from the start what you are going to do, otherwise its a dangerous and harmful waste of ressources.
Tech 2 is incredibly early, you're able to get flaks as quickly as 15 minutes into the game. The only game where that can be 'late enough' is a 1v1 on something like Close Encounters, with only 9 planets total and the destruction of your flagship really is the end of the game because you have no time or income to recover. Furthermore, early level Sovas only have 3 squadrons (at level 4, 2 until level 3). And still futhermore, while it may take you longer to research flaks than for your opponent to do a beeline straight to your homeworld, you still have your own capital ship and your own frigates as well.
also, its direct power isn't that bad, if you take those missile batteries and the added mobility via fighters into consideration. I'd have to test it, would be interesting to see if a lvl 3 sova could take down a lvl 3 kol with a bit of maneuvering.
It can. But its direct power is bad compared to a Kol's, and missile batteries are indirectly tied to it, not directly. But on the flip side, it can't go toe to toe with a bunch of gauss platforms, or a bunch of ships nearly as well as a Kol can. And you can't keep the Sova out of combat forever. Its squadrons alone don't match the versatility and firepower of a capital ship, so if you leave the Sova out and just send your frigates in, an enemy fleet with a capital will always overpower your frigates, despite the Sova's bombers.
alright that was a lot on early game, now late game: again, you have the power to force your enemy into the (counter) offensive. if you have other capital ships you have to move in to destroy structures which may bring you into defensive range or split up your formation, and also cancels your ability to instantly jump out again. you can sit there and get money and at some point your enemy will just have to attack you. also, if you think of it, flaks are pretty easy targets. even if the enemy has some, you can still put your fighters on dock wait for the flaks to come and then use lrms other ships to take them out fast and use your bombers thereafter.
In the late game, it's even easier to deny the Sova its advantage. Only very high level Sovas can field many squadrons, and it's a lot easier to build a few flaks and hangar defenses than it is to get a Sova to level 10. For example, if you watch the 3v3 replay Ron posted, at one point I maneuvered my fleet behind the main defensive line to bomb a planet, while he had I *think* 2 Sovas and hangar defenses spitting out fighters and bombers. My Sentinels (Vasari flaks) managed to keep them all at bay and I bombed the planet down and only lost a handful of frigates. And while the Sova can sit there and get money, in the late game you won't feel the loss of a percentage of one planet's income, nor will he gain a noticeable increase in his own income.
maybe get this a bit shorter again: what makes the sova powerful is its strong sieging abilites coupled with its nature to remain in jump-out distanance while still doing harm and its general flexility to counter a nice array of different threats, from bombers to frigates of other capships. and for all those benefits I'm not sure if there are enough drawbacks.
But the thing is, it can't do all of that at once. It's very rare for capital ships to get very high in level in Multiplayer, because people spike them pretty efficiently. So for the early/mid levels, if you make it an effective embargo boat, it won't have fighter/bomber damage or good missile pods. If you give it good missile pods and some fighter/bomber damage, it won't have Embargo. If you focus on fighter/bomber damage, it will have very weak pods and weak Embargo. That's how it works

Most Sovas will never be able to do everything at once. And really, its squadrons become fairly easy to deal with it within the first 30 minutes of the game, and its Embargo has little meaning to an empire controlling even 5 planets or with a trade network set up.
So no, I still don't agree that it needs a nerf, nor have you suggested exactly
what to nerf in it

In the end, you could make a case for why every capital ship should be nerfed because they stand out in one specific way. But all that means is, in the grand scheme of things, everything is unique and has a use, not that everything should be nerfed