To note, what others said above about companies pulling funding from existing teams due to excess application load is very true; we’re currently dealing with the consequences of this as one of our sponsors received an unusually high number of applicants this year and was unable to continue funding our registration cost.
Beyond that though, I’ve included a short list of teams with accessible applications or employee grant programs that regularly donate to FIRST teams; there’s a good chance you already know of most of these, and it’s by no means comprehensive – we’ve been sponsored by multiple companies that don’t commonly support FRC teams, and I’ve excluded grantmakers which have stringent requirements (e.g. IFI), are not accepting unsolicited requests (e.g. Abbot Fund), or which are no longer operational (e.g. Brin Wojcicki Foundation) – but hopefully a few may be helpful:
Department of Defense (Employee)
General Motors (Employee)
Lockheed Martin (Application)
Western Digital (Application)
BAE Systems (Application)
Dell Foundation (Application)
Intuitive Surgical (Application)
NASA (Rookies, At-Risk-Teams, Employee)
These really are just the base-level sponsors for teams in my area, so if you have questions about teams not on the list, do ask!