Server Response 429 - InFlightReq?

I've got Traefik v2.5 running in Docker and have a largely successful experience for well over a year now. I have one web app (a board game node.js app) that can never seem to fully load the page (unless I bypass Traefik and go directly to the local IP). I get anywhere from 5-20 assets fail to load per the console if I inspect the page. My Traefik debug logs are below but I can't make any sense of them. I'm wondering if this has anything to do with too many in-flight requests. I don't have anything set for a max amount, so I'm not sure what the default is. I'm tempted to just put a really high number in there at least to troubleshoot, but I'm not sure what I'll learn if it does or doesn't work...

Thanks everyone!

10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/ma/industrialist.png HTTP/2.0" 429 17 "-" "-" 629 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/hex_volcanic.png HTTP/2.0" 429 17 "-" "-" 633 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/hex_blue.png HTTP/2.0" 429 17 "-" "-" 632 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/colonies-planets/enceladus.png HTTP/2.0" 429 17 "-" "-" 634 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/colonies-planets/europa.png HTTP/2.0" 429 17 "-" "-" 635 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/colonies-planets/io.jpg HTTP/2.0" 429 17 "-" "-" 637 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/colonies-planets/titan.jpg HTTP/2.0" 429 17 "-" "-" 638 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/resources/floater.png HTTP/2.0" 429 17 "-" "-" 639 "tm-rtr@file" "-" 0ms
10.0.0.1 - - [01/Jan/2022:01:56:29 +0000] "GET /assets/colonies-planets/triton.jpg HTTP/2.0" 429 17 "-" "-" 640 "tm-rtr@file" "-" 0ms