Steps to reproduce the issue

Create a scheduled task to Sleep for 5 seconds with
Execution Rule = Interval, Minutes
Interval in Minutes = 60

In Options enable Web cron and copy your secret URL - mine is, note no ID= in the url:

http://example.com/index.php/component/ajax/?plugin=RunSchedulerWebcron&group=system&format=json&hash=ireiiA30GL9TN4VHGYk5

it says "By default, requesting this base link will only run tasks due for execution"

Expected result

Visit your url = note it hangs for 5 mins...

This should mean that on first run it should sleep for 5 seconds, then should never run again until 60 mins have elapsed, and then on the next run It would sleep for 5 seconds. Correct?

Visit your url = note it hangs for 5 seconds...
then in 1min
Visit your url = note it hangs for 5 seconds...
then in 1min
Visit your url = note it hangs for 5 seconds...

Actual result

Visit your url = note it hangs for 5 seconds... check Job Execution History - note the times have changed
then in 1min
Visit your url = note it hangs for 5 seconds... check Job Execution History - note the times have changed
then in 1min
Visit your url = note it hangs for 5 seconds... check Job Execution History - note the times have changed
then in 1min
Visit your url = note it hangs for 5 seconds... check Job Execution History - note the times have changed

basically on every load of the web cron url, the task is being fired regardless of the schedule...

If you enable logging for your task you can also see its running on every call..

2021-12-27	23:40:56	INFO	Running task#07 '1sleep1'.
2021-12-27	23:40:56	INFO	Task> Starting 5 timeout
2021-12-27	23:41:01	INFO	Task> 5 timeout over!
2021-12-27	23:41:01	INFO	Successfully finished task#07 in 5.01 (net 5.01) seconds.
2021-12-27	23:41:03	INFO	Running task#07 '1sleep1'.
2021-12-27	23:41:03	INFO	Task> Starting 5 timeout
2021-12-27	23:41:08	INFO	Task> 5 timeout over!
2021-12-27	23:41:08	INFO	Successfully finished task#07 in 5.01 (net 5.01) seconds.
2021-12-27	23:41:11	INFO	Running task#07 '1sleep1'.
2021-12-27	23:41:11	INFO	Task> Starting 5 timeout
2021-12-27	23:41:16	INFO	Task> 5 timeout over!
2021-12-27	23:41:17	INFO	Successfully finished task#07 in 5.01 (net 5.01) seconds.
2021-12-27	23:41:19	INFO	Running task#07 '1sleep1'.
2021-12-27	23:41:19	INFO	Task> Starting 5 timeout
2021-12-27	23:41:24	INFO	Task> 5 timeout over!
2021-12-27	23:41:24	INFO	Successfully finished task#07 in 5.01 (net 5.01) seconds.

@ditsuke