WhatsApp "Couldn't download audio. Try again. If the problem keeps happening, try turning off Wi-Fi or VPN, or connecting to a different Wi-Fi network."

Exactly like this post: https://discussions.apple.com/thread/250583927

I was able to solve this issue if anyone needs the info in the future.

Most replies to this problem are ridiculous and are only suggestions by well-meaning folks that don't know a solution.

My fix: Go to Settings>Wi-Fi and select the information button (encircled "i") next to the wifi network to which you are connected. Scroll down to the DNS section and select "Configure DNS". Change the DNS configuration to "Manual" and add a DNS server, such as Google's 8.8.8.8.

I was using an iPhone 8 on iOS 13.3 when I did this.