I too was quite happy to see 100SCs roll over, then noticed it reset to 50, and realised I thought it should be 200!
Before the rollover I was silver and had 245 SCs.
Of that, 40 were from flights (Covid, eh?), 10 from BP incentive and the rest were bonus Status Support
So when they rolled over, I retained Silver and got 100SCs then reduced to 50. Makes sense, as it did say in the T&Cs for status support that it was a MAXIMUM of 100 for Silver, and they would only rollover earned points, not bonus.
All happy so far until I remembered I was also Points Club Plus until the end the status year, which promised to roll forward a maximum of 100 status credits, and the T&Cs say that's in addition to the status support incentive, but makes no mention that it doesn't apply to bonus SCs.
Spoke to QF who keep mixing the two up. If they'd just say "hey, you only earned 50 and you got all of them rolled over" I would probably grumble and accept it. Instead they kept trying to insist the schemes are somehow related (when the T&Cs say they're independent) and refuse to acknowledge the fact that points club plus didn't exclude bonus credits.