A few more words about variance and bankroll management. OP began playing regularly on Pokerstars in may 2023, and until december 2023 he was a slightly losing to break-even player. Then just before X-mas in december 2023 began a sunrun fueled by some large cashes, which seem to originate from some satellite wins, where he then won some bounties in the target tournments. All in all he won around $220 in 40 days, and have now lost around $35 in the last 15 days.
But its completely normal and expected, that a sunrun always comes to an end. And the "downswing" or "rut" is only around 10 BIs in the SnGs, he mainly play. 4 x $5 and 6 x $2 or something like that. A 10 BI downswing is absolutely nothing and will happen all the time. So this is simply something, we need to be mentally prepared for, weather we play for profit or for fun. There is no reason to feel "down", because this happen, or question your play. Sure its always good to study, but losing 10 BIs over 23 games is not a reason, why now you suddenly need to study more.
As for bankroll management and the 50 BI rule for single table SnGs, the idea is to limit wild swings to our bankroll. Its theoretically possible to avoid "going broke" using more aggressive bankroll management, as long as we move down after losing. But its not ideal to play $10 SnGs one week and then $1 SnGs a few weeks later, because we lost 90% of our roll. We want the process of moving up to be a more steady one, where an attempt to move up might fail, but where we dont need to do more than drop back to the level, we came from.
Lets say, we have $140, as OP apparently did. Then we play $2 SnGs, and its entirely possible to lose 20-25 BIs due to some bad luck. Now we have $90-100, and therefore starting the next session we move down to $1 games , until we are back above $100. This mean, we can now lose a further 45-50 BIs, before we need to move down to $0,5 games, and this is pretty unlikely, if we are a winning player. So the vast majority of the time we will only need to move down to $1 games, and hopefully we are soon back to $2 games again.