Mined basically in 2 pools that control at least 60% of hashrate.
Discussion
boy do I have some bad news for you
😬

(its also known that some of those smaller pools are just fronts for Antpool)
A potential problem both Bitcoin and Monero share. At least Monero has decentralized mining with P2Pool available though. Afaik Bitcoin doesn't have an equivalent even with StratumV2