The size of an exported .ics file has varied over the years from 100KB to 1KB. Currently it appears to be around 29KB.
Most of this size appears to be created by the use of historical time zones which specify daylight saving times from the 1800s onwards.
Is that really necessary, or useful?
Having developed a python script to reduce ‘bloat’, my archive of some 25k events has shrunk from 2.4GB on disk to around 100MB.