The ARRL released ARLB011 reminding amateurs that updated Radio Frequency Exposure rules become effective on 3 May 2021.
These are the same rules that have been in effect since 1997. The primary change is that amateur radio stations are no longer categorically exempt from performing an evaluation. The RF Exposure limits have not changed.
More details on the ARRL RF Exposure website. Resources available on that page are links to an ARRL FAQ their RF Exposure and You document, an extract from the chapter on conducting a station evaluation, forms you can use, and an online RF Exposure Calculator.
Here’s another RF Exposure calculator by VP9KF that displays the info in a different way including discussion of duty cycle of different modes.
You do not have to submit any information with the FCC. Simply complete the documentation and file it with your license documents.
The ARRL states that they will be updating their site with any applicable changes as they are identified.