Thanks for providing a link! This media file played back on my device without issues with v4l2slh265dec. Here is the video metadata for future reference as shown by mediainfo:
MediaInfo working sample
Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main
Codec ID : V_MPEGH/ISO/HEVC
Duration : 10 min 34 s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 60.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Language : English
Default : Yes
Forced : No
However, the following media file does not render correctly with visible artifacting near the bottom of the video:
https://www.libde265.org/hevc-bitstreams/spreed-1080p.mkv
MediaInfo broken sample 1
Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main
Codec ID : V_MPEGH/ISO/HEVC
Duration : 1 min 0 s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 29.970 (29970/1000) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Language : English
Default : Yes
Forced : No
Another file that has artifacts is the following: https://test-videos.co.uk/vids/bigbuckbunny/mp4/h265/720/Big_Buck_Bunny_720_10s_1MB.mp4
MediaInfo broken sample 2
Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L3.1@Main
Codec ID : hev1
Codec ID/Info : High Efficiency Video Coding
Duration : 10 s 0 ms
Bit rate : 842 kb/s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 30.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.030
Stream size : 1.00 MiB (99%)
Writing library : x265 2.6+49-7219376de42a:[Windows][GCC 7.3.0][64 bit] 8bit+10bit
Encoding settings : cpuid=1050111 / frame-threads=3 / numa-pools=8 / wpp / no-pmode / no-pme / no-psnr / no-ssim / log-level=2 / input-csp=1 / input-res=1280x720 / interlace=0 / total-frames=0 / level-idc=0 / high-tier=1 / uhd-bd=0 / ref=4 / no-allow-non-conformance / no-repeat-headers / annexb / no-aud / no-hrd / info / hash=0 / no-temporal-layers / open-gop / min-keyint=25 / keyint=250 / gop-lookahead=0 / bframes=4 / b-adapt=2 / b-pyramid / bframe-bias=0 / rc-lookahead=25 / lookahead-slices=4 / scenecut=40 / radl=0 / no-intra-refresh / ctu=64 / min-cu-size=8 / rect / no-amp / max-tu-size=32 / tu-inter-depth=1 / tu-intra-depth=1 / limit-tu=0 / rdoq-level=2 / dynamic-rd=0.00 / no-ssim-rd / signhide / no-tskip / nr-intra=0 / nr-inter=0 / no-constrained-intra / strong-intra-smoothing / max-merge=3 / limit-refs=3 / limit-modes / me=3 / subme=3 / merange=57 / temporal-mvp / weightp / no-weightb / no-analyze-src-pics / deblock=0:0 / sao / no-sao-non-deblock / rd=4 / no-early-skip / rskip / no-fast-intra / no-tskip-fast / no-cu-lossless / no-b-intra / no-splitrd-skip / rdpenalty=0 / psy-rd=2.00 / psy-rdoq=1.00 / no-rd-refine/ no-lossless / cbqpoffs=0 / crqpoffs=0 / rc=abr / bitrate=872 / qcomp=0.60 / qpstep=4 / stats-write=0 / stats-read=0 / ipratio=1.40 / pbratio=1.30 / aq-mode=1 / aq-strength=1.00 / cutree / zone-count=0 / no-strict-cbr / qg-size=32 / no-rc-grain / qpmax=69 / qpmin=0 / no-const-vbv / sar=1 / overscan=0 / videoformat=5 / range=0 / colorprim=2 / transfer=2 / colormatrix=2 / chromaloc=0 / display-window=0 / max-cll=0,0 / min-luma=0 / max-luma=255 / log2-max-poc-lsb=8 / vui-timing-info / vui-hrd-info / slices=1 / no-opt-qp-pps / no-opt-ref-list-length-pps / no-multi-pass-opt-rps / scenecut-bias=0.05 / no-opt-cu-delta-qp / no-aq-motion / no-hdr / no-hdr-opt / no-dhdr10-opt / analysis-reuse-level=5 / scale-factor=0 / refine-intra=0 / refine-inter=0 / refine-mv=0 / no-limit-sao / ctu-info=0 / no-lowpass-dct / refine-mv-type=0 / copy-pic=1
Codec configuration box : hvcC
Do you observe the same artifacts for the broken samples?