Warped flapper door on dryer vent

[fixt]

Dryer vent flapper is warped and does not close completely. Rodents/insect might be able to get in. Is it possible to replace just the flapper? Did a google search and it appears they don't make replacement flapper doors. Saw a bunch of recommendations on replacing the entire dryer vent as a DIY. Can someone tell me how difficult it would be replace the entire dryer vent in my case (see pictures) - it appears that it's embedded in the siding and I don't want to mess with the siding.


Dryer and bathroom vents:


Warped flapper:


This is what a good flapper looks like:

 

[Snoonyb]

Welcome.
The flapper is reasonably malleable, by hand.
Any intrusions would be flushed out at the next regular usage.