iCarsoft calls it the EGS as well.Altide8: note that code p2225-1 is coming from your ENGINE module.
So the Transmission module is telling the Engine module that there is an existing fault... but: the TCM doesn’t clear its codes, so when you clear the code from the ECM it has no effect on the status of the stored TCM code, and the ECM code will reappear.
You’ll want to go into the Read/Clear Codes menu for the Electronic Transmission Control Module (or whatever the iCarsoft calls the NAG1 trans controller?) and read/clear the codes from there. Assuming this was caused by your low-voltage event, the codes should then stay cleared. If there are other underlying issues you’ll need to continue your diagnostics, and the TCM fault codes you read should provide you a direction to pursue. If there’s a wiring issue (rodent damage? wet/leaking 13-pin connector socket?) I would expect to find something like code 260x stored in the EGS/TCM fault list?