Who is responsible for the brawl in Parliament?

Colombo (News1st): Deputy Speaker Ananda Kumarasiri says that the speaker will take the necessary steps, following the analysis of the report submitted by the committee to investigate into the parliament brawls that took place in parliament last November. This report was submitted to the speaker on the 22nd of January. The Criminal Investigations Department has also commenced investigations into this matter. Details of the report, submitted by the committee led by Deputy Speaker Ananda Kumarasiri, was revealed by BBC News Sinhala recently. The report reveals that action should be taken against 59 MPs, who violated sections of the powers and privileges act of parliament, by their unruly behaviour in Parliament on the 14th, 15th, and 16th of November last year. Among the 59 MPs, 54 MPs represent the UPFA, 4 MPs represent the UNP and 1 MP represents the JVP. According to MP Vijitha Herath, accusations have been levelled against him, due to him approaching the Speaker and attempting to address the speaker on the 14th of November.

But, how did this issue arise?

https://youtu.be/huXlBM2-ONQ As per standing order 135 of the parliament, an MP has the right to propose the suspension of standing orders, and we will not challenge this. However, Standing order 135 also states, that unless the suspension of a standing order is proposed by a Cabinet Minister, such a proposal must be approved by more than 20 MPs within the chamber of parliament.

Was this proposal approved in parliament on the 14th of November, in a manner that guarantees democracy?

https://youtu.be/02qmYzDW3_o This was MP Sumanthiran's behaviour on the 23rd of November last year when the speaker called for voting for the selection committee, which was appointed by him. When senior MP Lakshman Kiriella called for voting and opted to act in a democratic manner, it was MP Sumanthiran who intervened. https://youtu.be/BgYsDTvy8SM Should not the behaviour of MP Sumanthiran, that put Parliament democracy and his party under threat, be subject to investigation? If proceeding towards the Speaker's chair to request for a vote to be called by MP Vijitha Herath, prompted for investigations, should not the behaviour of MP Sumanthiran also be subject to investigation?