Gig platforms neither decrease your rating / deplatform you if you decline work.
"Rating" is generally accepted as the "star rating" or some other statistics that users will see. Yes your "acceptance rate" will be affected, but this is a vanity metric that is secret to the driver => It is irrelevant.
There is no mention of deplatforming in any of these articles.
https://help.doordash.com/dashers/s/article/Dasher-Ratings-E...
https://driver-support.grubhub.com/hc/en-us/articles/3600298...
https://taskers.taskrabbit.com/2018/06/01/acceptance-rate-wh...