I've followed all instructions this far.
As far as the cable, I'm using a Zeskit Maya 8K 48Gbps Certified Ultra High Speed HDMI Cable 16ft, 4K120 8K60 144Hz eARC HDR HDCP 2.2 2.3 Compatible with Dolby Vision Apple TV 4K Roku Sony LG Samsung Xbox Series X RTX 3080 3090 PS5.
:edit: I have to use this cable, because I put in one of these things to hide cables in the wall, and that's the only cable I found that's long enough; but I'll try using the cable that came with the Xbox to rule out an issue with the Zeskit cable.
It depends on what you are using. If it's the same blu-ray player you used with the old TV, I wouldn't worry too much, but if it's a 4k blu ray player or PS5/XBSX then yeah I'd get new cables. HDMI cables have changed a bit in 20 years so probably just a good idea to upgrade them. I just got some new cables myself, but I got a PS5 and needed a longer cable than what was included, so I got a HDMI 2.1 compatible cable. This is what I got, a little pricey, but good quality:
https://www.amazon.com/gp/aw/d/B07S1BNM7K/ref=ox_sc_saved_image_10?smid=A7EB2YHL3E081&psc=1
Here is the cable I bought. I don't see the silver badge anywhere on or in the box. HDMI 2.1 I bought
I don't think certification is that critical. It may mean that the company simply hasn't submitted samples and paid money for the certification. You want it to say "Ultra High Speed."
The Monoprice cables are certified, though. https://www.monoprice.com/category/cables/hdmi-cables/hdmi-cables?&menuDisStr=hdmi%20cables&v_Bandwidth_uFilter=48Gbps&TotalProducts=35
Monoprice wanted a fortune for the length I needed, so I also bought this Zeskit, which says it's certified: https://www.amazon.com/gp/product/B07S1BNM7K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1