If you want something super sturdy, this is what you want. Made for extreme environments like trucks, boats and planes. Just got mine and really like it. You get what you pay for. Can't believe people rely on $9.99 vent mounts for a 2k phone that could easily break if it falls from the mount at a high speed but to each their own.
https://www.amazon.com/dp/B00B4IXTMI/ref=cm_sw_r_cp_apa_i_vGF.FbCXZG7K2?_encoding=UTF8&psc=1
The best mount I've found so far is from RAM mounts. https://www.amazon.com/dp/B00B4IXTMI?psc=1&ref=ppx_yo2ov_dt_b_product_details I've been using the same one since I bought the fold 3 and still works perfect for my fold 4. It's a bit on the expensive side, but I drive a semi-truck and this mount keeps my shit in place.
RAM Mounts RAM-B-166-UN8U X-Grip with RAM Twist-Lock Suction Cup Mount for 7"-8" Tablets with Medium Arm for Vehicle Windshields https://www.amazon.com/dp/B00B4IXTMI/ref=cm_sw_r_cp_api_glt_fabc_HP9HMHK7EWFZJXNAXANR
Had mine for a couple years. I fly a 182 and mount it just to the left. Has worked perfectly.
https://www.amazon.com/gp/product/B00B4IXTMI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
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That is what I use for my Fold 4. Used it with my Fold 3 as well, expensive but rock solid and would recommend. I have a mount for my Tab S8 Ultra from them that uses the same mounting mechanism and never had any issues.
I've said it a few times, but RAM make a small (7-8" tablet x grip mount that works fantastic with the z fold in tablet mode. It's a little pricey, but very high grip. You can get a b-ball adhesive mount, so you don't need the suction cup mount.
It's pricy and and not that pretty, but I like the Ram mounts X grips the best. This one fits it unfolded. https://www.amazon.com/dp/B00B4IXTMI/ref=cm_sw_r_cp_apa_i_rV6zFb0NBPFEX
Do you use this by any chance? It's what I'm looking at getting but $60 is a lottttt