openoffice is an apache project, created when oracle gave them the code and rights to the openoffice project. ibm later donated symphony to them. anyone familiar with apache knows they do things their own way, and usually slowly.

libreoffice originated from a fork when openoffice’s status under oracle was in doubt. it progresses faster than apache, as most developers also switched.

onlyoffice is an entirely different application. decent enough, but with its own quirks. it can also be slow on lower-spec systems due to the heavy reliance on js. originally a latvian-russian project, it was reorganized (via new corporate entities in uk and sg) to hide the russian ties for ‘reasons’.