I'm pretty sure that "don't operate your radar in enemy airspace" is right below "don't email your flight plan to the enemy" on the list of tips for stealth pilots who want to survive a mission.

stealth does in general go out the window when you turn on your radar. It's much like dressing in black and then running around with a flashlight at night. (and yes, there are equivalents to the various forms of night vision here, with associated tradeoffs)

Doubt: the APQ-181 radar on the B-2 is a Ku band radar, about 15 GHz. Tamara is about 1 GHz. This is entirely incompatible frequency ranges.

Also, the APQ-181 is a LPI radar, which means it’s specifically designed to avoid correlation of signals such that you can track by the signals emitted. There are presumably some downsides to working in LPI, but the upside is that the signal is designed to be indistinguishable from an increased noise floor.

It turns out for the Iran drama, that radar's like the Tamara have to survive the F-35s first, then the F-15s…

Which they don't.

Then the B-2s fly in in unopposed.

The key to the B-2s is dropping the F-35s. Which seems to be hard.