Curl4, Quantmod, tseries and forecast

Dear All,
I have just upgraded to Debian stable 10 and rebuilt most of the R
packages.
I use the R backported packages from here

https://cran.r-project.org/bin/linux/debian/#debian-buster-testing

for the core system.
I encounter some issues when updating quantmod, tseries and forecast.
For instance, see the following

install.packages("tseries")

which finally fails with the following message

** byte-compile and prepare package for lazy loading
Error in dyn.load(file, DLLpath = DLLpath, ...) :
  unable to load shared object '/usr/local/lib/R/site-library/curl/libs/curl.so':
  /usr/lib/x86_64-linux-gnu/libcurl.so.4: version `CURL_OPENSSL_3' not found (required by /usr/local/lib/R/site-library/curl/libs/curl.so)
Calls: <Anonymous> ... asNamespace -> loadNamespace -> library.dynam -> dyn.load
Execution halted
ERROR: lazy loading failed for package ?tseries?
* removing ?/usr/local/lib/R/site-library/tseries?
* restoring previous ?/usr/local/lib/R/site-library/tseries?

Now I have curl44 installed on my system because that is what Debian
prrovides me with (and for the overwhelming majority of my packages it
is not a problem).
Please find below my sessionInfo().
Any suggestion is appreciated.

Cheers

Lorenzo

sessionInfo()

R version 3.6.0 (2019-04-26)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Debian GNU/Linux 10 (buster)

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.8.0
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.8.0

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8
 [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] compiler_3.6.0 tools_3.6.0