error: certificate has expired

[JanUrlaub]

MMM-NextCloud-Tasks does not work anymore on my site. I get this error when I open the magic mirror site.
Its may be the switch of Letsencrypt to a new root certificate. The nextcloud instance gets its certifcates from Letsencrypt.
But maybe someone also search for this error like me and also found no solution to fix this.
Can you help? Maybe this help can also added to the error message.

I tried this, but it seems not enogth.

sudo npm install -g npm
sudo npm install -g n

[
"WebDav: Unknown error: ",
{
"message": "certificate has expired",
"name": "Error",
"stack": "Error: certificate has expired\n at TLSSocket.onConnectSecure (_tls_wrap.js:1501:34)\n at TLSSocket.emit (events.js:315:20)\n at TLSSocket._finishInit (_tls_wrap.js:936:8)\n at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:710:12)",
"config": {
"url": "https://janf.name/remote.php/dav/calendars/firefly/beide/",
"method": "propfind",
"headers": {
"Accept": "text/plain",
"Authorization": "Basic xxx",
"Depth": "1",
"User-Agent": "axios/0.21.1"
},
"transformRequest": [
null
],
"transformResponse": [
null
],
"timeout": 0,
"responseType": "text",
"xsrfCookieName": "XSRF-TOKEN",
"xsrfHeaderName": "X-XSRF-TOKEN",
"maxContentLength": -1,
"maxBodyLength": -1
},
"code": "CERT_HAS_EXPIRED"
}
]