Well, after further research, I think that what I said is most likely wrong. As not explicitly specified by Panasonic in the user manual, the given mode 1 and 2 restrictions are probably for 8 bit SDR and not 10 bit HDR10 or 12 bit Dolby Vision which require additionnal bandwidth.
4K, 24 Hz, 10 bit, 4:2:0 (native HDR10 disc encoding) requires 8.91 Gbps
4K, 24 Hz, 12 bit, 4:4:4 (player upsampling) requires 13.37 Gbps
4K, 60 Hz, 10 bit, 4:2:0 (native HDR10 disc encoding) requires 11.14 Gbps
4K, 60 Hz, 12 bit, 4:4:4 (player upsampling) requires 24.06 Gbps
Obviously the latter is not possible on this TV, even with Mode 2, it would require HDMI 2.1.
For the others I don't know, it depends on the Mode 1 bandwidth. If it's only 9 Gbps instead of 18 Gbps, then indeed maybe it won't work with HDMI 3 or 4.
Sources:
https://i2.wp.com/semiengineering.c...8/04/hdmi-2.1-fig-1-resolution-tabe.jpg?ssl=1 &
HDMI Data Rates for 4K HDR