Unfortunately there are WP Plugins (well, probably others too) that load outdated, unscoped Composer libs. See an example https://wordpress.org/support/topic/fatar-error-4/ Typesense PHP Client uses monolog too, and of course, a newer version will then fatal with that WP Plugin installed yes, we can scope our code when integrating Typesense but honestly, it proves to be a huge PITA. I am wondering, is monolog needed for Typesense to function? Could I somehow exclude it?

It's only used for logging... So not strictly needed

Yeah I ended up scoping my code. I hate it but “we’ll fix it maybe in the next three releases” is just typical answer for “meh. We don’t care”