Your options basically are:
- Upgrade to Enterprise to increase it
- Change it to fire and forget, return instantly and do the work in the background.
- Unproxy the domain and lose Cloudflare’s benefits like CDN/WAF. If it’s just you doing maintenance work, you could bypass Cloudflare and allow yourself to connect directly.
- Change it to a job based system where it kicks off the job in the background and the client using JS queries for job status until completion.
- Make the job not take 100 seconds by making it faster or splitting it into parts (may not be doable depending on what it is)
If it doesn’t cancel the work even if the request gets cancelled, you also have the option of doing nothing at all. If it’s just for maintenance, execute it and watch logs (if any) to ensure it worked.
Not sure what else you’re looking for.