Too many changes and updates required due to continuous rollout of unfinished fast moving target Gutenberg in core leads to abandoning of free themes by authors.

This outcome was crystal clear from the beginning for everybody who saw the rollout concept, many have warned that exactly this would happen.

Free community work of authors has been overstressed since WP 5.x, authors now move on to lite/paid to cover the required extra time for Gutenberg or simply abandon everything. Thats same for plugins.

As simple as that.