Request: show regex, responsible for blocking

ran pihole -up

pihole now crashes regulary. tried to remove old database and logs, restarted, same result:
The log (partial):

[2020-02-10 15:18:11.865 22402] ERROR: Encountered serious memory error in findForwardID()
[2020-02-10 15:18:14.597 22402] New forward server: fdaa:bbcc:ddee:2::5552 (-1/1024)
[2020-02-10 15:18:14.597 22402] FATAL: Trying to access forward ID -1, but maximum is 1024
[2020-02-10 15:18:14.598 22402]        found in findForwardID() (src/datastructure.c:54)
[2020-02-10 15:18:14.598 22402] ERROR: Encountered serious memory error in findForwardID()
[2020-02-10 15:18:14.599 22402] New forward server: fdaa:bbcc:ddee:2::5552 (-1/1024)
[2020-02-10 15:18:14.599 22402] FATAL: Trying to access forward ID -1, but maximum is 1024
[2020-02-10 15:18:14.599 22402]        found in findForwardID() (src/datastructure.c:54)
[2020-02-10 15:18:14.599 22402] ERROR: Encountered serious memory error in findForwardID()
[2020-02-10 15:18:25.022 22402] !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[2020-02-10 15:18:25.022 22402] ---------------------------->  FTL crashed!  <----------------------------
[2020-02-10 15:18:25.022 22402] !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[2020-02-10 15:18:25.022 22402] Please report a bug at https://github.com/pi-hole/FTL/issues
[2020-02-10 15:18:25.022 22402] and include in your report already the following details:
[2020-02-10 15:18:25.022 22402] FTL has been running for 711 seconds
[2020-02-10 15:18:25.022 22402] FTL branch: release/v5.0
[2020-02-10 15:18:25.023 22402] FTL version: vDev-fb01e09
[2020-02-10 15:18:25.023 22402] FTL commit: fb01e09
[2020-02-10 15:18:25.023 22402] FTL date: 2020-02-10 10:20:26 +0100
[2020-02-10 15:18:25.023 22402] FTL user: started as pihole, ended as pihole
[2020-02-10 15:18:25.023 22402] Compiled for armhf (compiled on CI) using arm-linux-gnueabihf-gcc (Debian 6.3.0-18) 6.3.0 20170516
[2020-02-10 15:18:25.023 22402] Received signal: Segmentation fault
[2020-02-10 15:18:25.023 22402]      at address: 0xf3afe99c
[2020-02-10 15:18:25.023 22402]      with code: SEGV_MAPERR (Address not mapped to object)

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see also here.
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