'Server certificate verification failed' error in shiny app

I have a shiny application hosted on shinyapps.io that has a functionality to display spatial data from a WFS service. The service had been working normally for the past few months, until the last week when the application could no longer start, with the following error:

Warning in CPL_read_ogr(dsn, layer, query, as.character(options), quiet,  :
  GDAL Error 1: server certificate verification failed. CAfile: none CRLfile: none
Error in value[[3L]](cond) : 
  Cannot open "https://firms.modaps.eosdis.nasa.gov/mapserver/wfs/South_America/####api-key####/?SERVICE=WFS&REQUEST=GetFeature&VERSION=2.0.0&TYPENAME=ms:fires_modis_24hrs&STARTINDEX=0&SRSNAME=urn:ogc:def:crs:EPSG::4326&BBOX=-18,-55,-27,-48,urn:ogc:def:crs:EPSG::4326"; Check connection parameters.

I haven't found a solution to the problem since the app is running on my local machine with no problem.

The wfs service to which the app connects is NASA's FIRMS (Web Services - WFS - NASA | LANCE | FIRMS) and the script used to connect is as follows, with the proper api key:

st_read('https://firms.modaps.eosdis.nasa.gov/mapserver/wfs/South_America/####api-key####/?SERVICE=WFS&REQUEST=GetFeature&VERSION=2.0.0&TYPENAME=ms:fires_snpp_24hrs&STARTINDEX=0&SRSNAME=urn:ogc:def:crs:EPSG::4326&BBOX=-18,-55,-27,-48,urn:ogc:def:crs:EPSG::4326')

Any help in solving this problem is welcome.