Jira integration changes cannot be saved using FireFox browser

Summary

Unable to save Jira integration setting on FireFox browser.

Steps to reproduce

  1. Setup Jira integration for a project (custom setting)
  2. Setup Jira integration at group level (default setting)
  3. Using FireFox browser navigate to project > Settings > Integration > Jira > switch to default setting > Click Save changes
  4. Observe the button to be spinning forever but no request is sent to GitLab.com
  5. Try the same thing on Google Chrome and see that the change persist

Example Project

https://gitlab.com/gitlab-gold/tristan/project/-/services/jira/edit

What is the current bug behavior?

Jira integration setting is not saved if changes are made on FireFox browser.

What is the expected correct behavior?

Changes should be saved regardless of browser.

Relevant logs and/or screenshots

image

Output of checks

This bug happens on GitLab.com; GitLab Enterprise Edition 13.7.0-pre 706d840b

Results of GitLab environment info

Expand for output related to GitLab environment info 

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check 
(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)


(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)


(we will only investigate if the tests are passing)

Possible fixes