If your company is using story points to “measure” developers, they are completely misusing that concept, and it probably results in a low-teamwork environment (as you describe).

The purpose of story points is so a team can say “we’re not taking more than X work for the next two weeks. Make sure it’s the important stuff.” It is a way to communicate a limit to force prioritization by the product owner.

And, in fact, data shows that point estimation so poorly converges on reality that teams may as well assign everything a “1”. The key technique is to try to make stories the same size, and to reduce variability by having the team swarm/mob to unblock stuck work.

Who creates these tasks? They need to close the year old items, reevaluate the work and break it down into sub-5-day chunks. If there are so many unknowns that it’s impossible to do that, the team needs to brainstorm how to resolve them.