Poll pipeline status rather individual report status when :pending payloads are received
Per #362845 (comment 1074856952), when the CI pipeline of the base branch of an MR is executed, comparison of reports is prevented until this is complete.
Currently the interface performs a poll per scanner every few seconds when this is the case, which could lead to an large increase on load for the GitLab API's if users wait on the MR page for these comparisons, as the number of polling requests increases per project scanner, and will continue for the duration of the CI execution on the base pipeline.
Possible Solution
Rather than poll the status of the reports, poll the status of the base branch's CI pipeline before attempting to pull the comparison reports. This will keep the polling to one request every few seconds, rather than a request per scanner every few seconds.