正しくはこうでした
$ bundle update --conservative scout_apm
:
Installing scout_apm 4.1.2 (was 2.6.8) with native extensions
Bundle updated!
これで直ったかな？
$ find vendor/bundle/ruby/3.0.0/gems/scout_apm-4.1.2 -type f -print0 | xargs -0 grep 'def find_by'
vendor/bundle/ruby/3.0.0/gems/scout_apm-4.1.2/lib/scout_apm/instruments/active_record.rb: def find_by_sql_with_scout_instruments(*args, **kwargs, &block)