Is there a possibility there will be more airplane crashes due to pilot error after the COVID pandemic?

Not a high one, no. If you knew anything about the industry currency and training standards and requirements you wouldn't have even asked. 

No.

Training programs using level D simulators are still in place, and pilots would still fly occasionally to maintain their license.

There was a shortage of pilots before the pandemic, and airlines are likely going to expect a return to the level of flight that existed before, so have the incentive to retain their pilots and to ensure they would not be blamed for having poorly trained pilots in command.

It is only reasonable to assume this will be a factor.

Pilots are still flying; there are less flights, but a legal minimum hours required (either in real planes or simulators) to retain their licenses. 

So, no...