For me, my password manager is the one absolute thing I want to be auditable. 1Password with its follower "who know people who designed it" reminds me of "trust me bro", "funds are SAFU" in cryptocurrency projects. Leaving LastPass in order to sign up for 1Password feels like out of the pan into the fire.
I've always use and will always recommend FOSS for password manager. I install Bitwarden on my technology-illeterate friends and family and I use KeepassxXC personally. I've looked briefly how vaults are encrypted in both software. The security is sound. Bitwarden was audited by Cure53[1] which is one of my favourite security auditing firm. (I highly recommend to read their audit of dovecot[2])
Anyway, you know what they say "fool me once…". I'll be eating popcorn when some claim will turn out to be false for 1Password…