The OpenCycleMap.org map tiles plugin is still avaible at the old IITC-me website, but is not available (anymore) at the new IITC.app website.
The map tiles are actually sourced from Thunderforest.
The map tiles are still free to use (if you request less then 150.000 tiles per month), but it requires a personal API key.
Without an API key, the Thunderforest map tiles will mention: API key required
Disable the OpenCycleMap plugin (and add-on) if you do not have an API key, and if you do not want to obtain a free API key.
This plugin is an Add-on to set up an API key so you can use the Thunderforest map tiles (from the original OpenCycleMap.org map tiles plugin).
To make things easier, the Add-on already includes the code from the OpenCycleMap plugin, so there is no need to get the separate plugin from IITC-me (which doesn't work anymore, because it still uses the old intel url: https://*.ingress.com/intel*).
The Add-on also adds another 5 map tiles from Thunderforest, so a total of 10 maps.
Check out the Thunderforest maps website for documentation about all these types of maps:
In the IITC menu you can find 'OpenCycleMap Addon'.
The menu will show some instructions and a button to open the Thunderforest website, and a button to enter your API key.
If you have the API key set up, you can use the Thunderforest map tiles, by selecting one of the Layers in the side pane.
If you see a watermark "API key required" on the map tiles, then your API key is invalid, or not set up correct.
In this case, fix the API key (maybe there is an extra space copied), or disable the Add-on plugin.
Make sure you check out other map tiles plugins from IITC.app website.
version 1.0.1.20220712.094300
version 1.0.0.20220710.185000
version 0.0.4.20210724.002500
version 0.0.4.20210421.190200
version 0.0.4.20210124.184400
version 0.0.3.20210121.224000
version 0.0.2.20210117.190200
version 0.0.1.20191023.001600